On Fri, 2015-11-27 at 18:21 +1100, Stewart Smith wrote:

Russell Currey [off-list ref] writes:

quoted

On Fri, 2015-11-27 at 16:40 +1100, Stewart Smith wrote:

quoted

Russell Currey [off-list ref] writes:

quoted

On BMC machines, console output is controlled by the OPAL firmware and
is
only flushed when its pollers are called.  When the kernel is in a
panic
state, it no longer calls these pollers and thus console output does
not
completely flush, causing some output from the panic to be lost.

This patch adds a new kmsg_dumper which gets called at panic time to
ensure
panic output is not lost.  It accomplishes this by calling
OPAL_CONSOLE_FLUSH
in the OPAL API, and if that is not available, the pollers are called
enough
times to (hopefully) completely flush the buffer.

You may want to add to commit message that this depends on:
https://patchwork.ozlabs.org/patch/547379/

It doesn't *depend* on it, it's just preferred.  It still works with older
Skiboot versions.  I will mention it in the actual commit message for the
next revision, though.

More meaning that it depends on that patch being merged before, say the
PCI hotplug patches, which add a *different* OPAL call at the same ID -
and that it depends on *this* patch with *this* API rather than a
modified one being merged.

Otherwise, if, say, I merged some other new OPAL call into skiboot
first, this patch would likely cause all sorts of trouble.

It's also a handy hint to Michael to ensure the skiboot side of things
is merged and okay before merging kernel things in.

That's a very good point I hadn't considered.  I'll make a note of it next
revision, especially given there are some additional changes required on the
Skiboot side of things.